The present invention relates to a display device and a semiconductor device to be employed thereon, especially one which can be preferably used for a display device having a display touch panel arranged to operate display drive and touch detection in a time sharing manner.
Many in-cell type display touch modules each having a display panel and a touch panel which are integrally laminated are adopted for mobile products including smart phones in recent years. In such an in-cell type display touch module, common electrodes are shared. On a display touch module like this, a semiconductor IC (IC: Integrated Circuit) operable to drive and control an in-cell type display touch panel and termed TDDI (Touch and Display Driver Integration) is employed; display driver and touch controller functions are integrated in the semiconductor IC. TDDI drives common electrodes concerned as common electrodes for display in a display drive period, and drives the common electrodes as drive electrodes each forming a sensor capacitance between itself and a detection electrode opposed thereto in a touch detection period.
US Patent Application Publication No. 2016/0085363 (Patent Document 1, which is U.S. Patent Application based on Japanese Patent Application (No. 2014-189705)) discloses a display device which performs display and touch detection alternately. A one-frame period is constituted by a plurality of units; each unit is divided into a period during which a video is displayed, and a period (a blanking period) during which video display is paused. The display device can perform the action of detecting a touch position in the blanking period. The display device includes an active matrix liquid crystal display panel having a plurality of pixel electrodes PE arranged in a matrix, and a control circuit CTR supplies a common voltage Vcom to the common electrodes COME of the plurality of pixel electrodes PE (FIG. 1). The common electrodes COME are formed in a stripe pattern; a capacitance CC for touch detection is formed between each common electrode and a corresponding detection electrode DETE (FIGS. 8 and 9).
The common electrodes COME are used for video display and also used as electrodes for detection of a touch position in this way, which are driven in a time sharing manner. Specifically, the common electrodes COME are driven by drive pulses TSVCOM in a period during which a display action is paused (FIG. 10B).
US Patent Application Publication No. 2014/0132525 (Patent Document 2) discloses a display touch panel of the same in-cell type, in which a self-capacitive method is adopted for touch detection. On a self-capacitive type panel 100, a plurality of electrodes 110 for touch detection are arranged as if they cover an entire surface of the panel as shown in FIG. 3. Each electrode 110 is connected with a sampling voltage generating unit 210 and a touch sensing unit 230 through a wiring line 120 and a switching unit 240.